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The green strategies used for daylighting involve many different disciplines, including mechanical, electrical and structural engineering as well as architecture and lighting design, and often are thought to increase first costs—and they can, if not properly implemented. Rendering: TK&A
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“We’d love a green building, but we can’t afford it.” Architects and interior designers around the country often hear this statement from clients. Despite the positive effects of a sustainably designed building on an organization’s bottom line—not to mention workplace productivity gains and demonstration of a strong commitment to sustainability—many clients opt not to pursue a green building because they perceive it as prohibitively expensive. In many cases, that perception simply isn’t true.
Recognizing a pervasive gap between perception and reality with regard to the cost of sustainable design, Cambridge, Mass.-based Tsoi/Kobus & Associates (TK&A) initiated a two-year study in 2008 to analyze cost premiums associated with sustainable strategies.
To organize the study into a format that would be recognizable to most industry experts, TK&A analyzed the LEED rating system credit by credit and strategy by strategy. To ensure a broad perspective, TK&A invited its frequent partners AHA Consulting Engineers, Lexington, Mass., and Vermeulens Cost Consultants, Toronto, and leading industry resource BuildingGreen to participate in the study (available for a fee at https://www.buildinggreen.com/ecommerce/). Comments on the assumptions and qualifications used by the authors are available in this month’s digital edition: www.rdmag.com/General/Laboratory-Design-News-Archive/.
Key findings: Base cost vs. premium and mainstream products
“The Cost of LEED” identifies several key findings that are essential to understanding the true cost of sustainable design strategies. Often the costs of sustainable design can be unnecessarily inflated because of miscalculations and misunderstandings of strategies.
First, it is important to not treat base project costs as part of sustainable design premiums. Some prerequisites and credits are required to ensure compliance with codes and local regulations and, therefore, are part of the base project cost. For example, credit SSp1: Construction Activity Pollution Prevention, which regulates erosion and sedimentation control, is considered a best practice and often is required by code. Another example would be Fundamental and Enhanced Refrigerant Management credits, which often can be easily achieved since certain types of refrigerants that violate these credits usually are prohibited in new equipment.
By identifying credits that can be readily attained with no cost premiums, designers can more easily demonstrate to clients that achieving incremental levels of sustainable design is economically possible. The same can be said for including sustainable design products that are becoming mainstream and carry the lowest cost premiums. For example, the authors discovered that low-flow fixtures, manual dual-flush toilets and waterless urinals have very low cost premiums and can provide big water savings. In addition, many building materials with recycled, rapidly renewable or low-VOC content have little to no cost premium. Double-glazed windows with low-E coatings and a low-SHGC (solar heat gain coefficient) also have a negligible premium.
Key findings: Synergies
“The Cost of LEED” database examines the financial and functional synergies of various LEED strategies to allow users to select a combination of strategies that best fits their budget and goals. The database promotes a holistic approach to green design by demonstrating how one strategy can be applied across many credits, how the costs of individual credits can be shared, how the integrated application of strategies can reduce first costs, and how cost synergies can shorten the payback time for a LEED-related investment. Even strategically choosing credits that have the largest number of cost synergies, such as Sustainable Site credits SSc1 and SSc2 and Energy and Atmosphere credit EAc1, can be a simple yet cost-effective tactic.
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Creating LEED-certified buildings combines multiple tactics, but some of these are required by code and should not properly be included in any calculation of a “LEED premium.” Diagram: TK&A
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For example, a green roof can: restore habitat, achieving credit SSc5.1; contribute toward maximizing open space, achieving credit SSc5.2; help achieve stormwater design credits SSc6.1 & 6.2; and be used to negate the heat island effect in credit SSc7.2, further contributing to a reduction in energy use through lessened cooling needs. Similarly, the cost of increased insulation and triple glazing can be more than offset by the savings achieved by purchasing a smaller HVAC system.
In addition, consider the sustainable design strategy of daylighting. An abundance of daylight has proven to improve the workplace environment and provide significant energy and operational cost savings. However, daylighting strategies can be complex. They span many different disciplines, including mechanical, electrical and structural engineering as well as architecture and lighting design, and often are thought to increase first costs—and they can, if not properly implemented.
High-performance windows are one such first cost. Windows with optimal light transmittance, low U-value and low SHGC allow more light in but also reduce solar heat gain, leading to decreased HVAC loads and associated energy use. By allowing more light in, these windows—in combination with daylight-sensitive light controls—reduce the need for artificial lighting, which reduces the electricity used for lighting and the internal heat gain that must be addressed by the cooling system, thereby reducing energy use.
“The Cost of LEED,” combined with energy modeling, allows users to analyze the cumulative effect of daylighting on building performance over the long term to better understand the true cost—and cost savings—associated with an investment in high-performance windows.
A sample calculation of daylighting synergies from the report appears in this month’s digital edition: www.rdmag.com/General/Laboratory-Design-News-Archive. Cost synergies by LEED category involved with decisions on daylight (IEQc8.1) can impact these other categories: SSc1 Site Selection; SSc2 Development Density; MRc1 Building Reuse; EAp1 Fundamental Commissioning; EAp2 Minimum Energy Performance; EAc1 Optimize Energy Performance; EAc3 Enhanced Commissioning; IEQc6.1 Controllability of Systems—Lighting.
Lab-Specific applications: What are they?
“The Cost of LEED” can be widely applied to lab buildings. Lab buildings use more energy and more water than comparably-sized office buildings, so the opportunities for conservation are greater and higher-performing systems can make a more significant impact on operating costs as a whole. Lab buildings also benefit from utilizing daylight, employee controls and LEED-appropriate materials in the same way that office buildings do.
Many cost synergies can be employed across sustainable design strategies for lab buildings. Several credit combinations are especially applicable to lab design.
Water-use reduction credits WEp1, WEc1, WEc2 and WEc3 can be combined with stormwater quantity reduction, credit SSc6.2, as well as an Innovation credit for process water use. Reducing water use in the plumbing fixtures can be accomplished by using reduced-flow fixtures, by capturing stormwater and reusing it to flush toilets and urinals (if waterless urinals are not used), and by capturing HVAC condensate and water rejected from pure-water filtration systems in the stormwater capture systems. If captured quantities allow, water may be directed toward make-up for cooling towers or toward landscape irrigation.
Energy-use credit EAc1 and ventilation credits IEQp1 and IEQc2 can be understood as cost synergies as well. Using differential occupancy-based demand control ventilation strategies in buildings that often require 100% outside air supply can reduce energy used, while still maintaining the ventilation quantities for indoor spaces above the minimums required for meeting the ASHRAE 62.1 Standard. In addition, the use of heat recovery for EAc1—flat plate, run-around loop or heat wheel, depending on systems used and availability of exhaust air—can reduce energy use during both heating and cooling operations.
By offering context for LEED-related decisions and promoting greater understanding of the true costs associated with green design and building, “The Cost of LEED” authors hope to encourage more clients and designers to embrace sustainable design as a sound—and achievable—business strategy.
To learn more about “The Cost of LEED,” contact Stephen Oppenheimer at soppenheimer@tka-architects.com. Purchase your copy of the report at https://www.buildinggreen.com/ecommerce/.
Sara Mills-Knapp, LEED AP, is sustainable design coordinator at the Cambridge, Mass.-based design firm Tsoi/Kobus & Associates (www.tka-architects.com). Stephen Oppenheimer, AIA, LEED AP, is an associate at the firm and founder of its Core Values Group, which is focused on developing a customized integrative design process, raising the firm’s level of sustainable design expertise, and advancing design through leadership in research. Robert Andrews Jr., PE, is a partner and director of the Sustainability Services group at AHA Consulting Engineers Inc., Lexington, Mass. For more information about “The Cost of LEED,” contact Oppenheimer at soppenheimer@tka-architects.com.
